1. Field of the Invention
This invention relates generally to window shade structures and more particularly to window shade structures having pleated shade panels.
2. Description of the Prior Art
Foldable or pleated window shade panels have become increasingly popular because of the aesthetically pleasing look of the pleated shades as well as the efficient manner in which the shades can collapse at the pleats when the shade is stacked during the raising of the shade. Such foldable window shades are made from fabric panels available in standard widths. The widest fabric panels are narrower than many window widths. Because of the limitations on fabric making equipment, it is not practical to produce wider fabric panels. Therefore, despite the advantages of such pleated shades, they may not always be used with some windows.
One way in which the industry has attempted to overcome the restrictions of standard width sizes is to attach two or more shade panels side by side so as to effectively increase the width of the entire shade panel structure. One such example of this attempt can be found in U.S. Pat. No. 3,946,788 to van Muyen. Van Muyen provides a plurality of pleated shade sections that are overlapped somewhat. The shade panel sections of van Muyen each have cord holes provided at opposite sides thereof. When van Muyen overlaps his shade panel sections, the holes are aligned so that lift cords may be provided through a vertical series of aligned holes.
Pleated window shades are known in the art in which the shades are provided with tabs formed on each pleat. Tabbed window shades are shown in U.S. Pat. No. 4,974,656 to Judkins. Such tabs formed on the pleats provide the shade construction with a location through which to run lift cords, the lift cord and lift cord holes being invisible from the front of the shade. The tabs also enhance energy efficiency and prevent light leakage by eliminating the need to place cord holes through the shade panels. The tabs also make the pleats stronger and more durable and are less likely to pull out in use, as well as enhancing the rigidity of the shade panels. Whether the pleated shade panels are tabbed or untabbed, there remains the restriction of the standard width of the shade panels.
When using the tabbed shades, it is not possible to simply overlap the shade panels to create the added width. This is because the tabs prevent the front face of one panel from mating with a rear face of another panel. Therefore, window shades having tabs and that are wider than the standard fabric panel widths are presently unavailable in the industry.